Gaskets are often used to seal mating mechanical components. One common application involves the placement of a gasket between a head and an exhaust manifold of an internal combustion engine. Another application involves gasket placement between the exhaust manifold and an exhaust pipe flange. Gaskets for either application are considered high temperature gaskets and more particularly exhaust manifold gaskets since they provide an exhaust seal that prevents the by-products of combustion exiting the combustion chamber from escaping a vehicle engine.
In a metallic laminate gasket for an exhaust manifold of an internal combustion engine, the gasket is formed from a plurality of metallic gasket layers laminated together. The metallic layers provide structural support between the manifold and engine block, and radial strength to resist gasket blow-out due to combustion chamber generated pressures. Typically, the metallic layers are laminated together by welding. However, welding is undesirable for a number of applications. For example, welding is a time consuming process and involves specialized tooling, thus increasing manufacturing costs. Further, the metallic layers may become warped, thereby compromising sealing effectiveness, due to the high weld temperatures generated. Additionally, weld beads formed by the welding operation may reduce the force available for sealing the gasket layers as weld beads can interfere with mating members before they are fully tightened together.
To avoid the difficulties associated with welding, it has been known to provide a metallic gasket with a plurality of bending strips that cooperate with holes for connecting first and second metal plates together. A hole is formed in the first plate while a bending strip extends from the second plate. The bending strip is passed through the hole of the first plate where it is bent over to engage an outer surface of the first plate. While the use of bending strips is less expensive than welding, a bending strip produces localized stress loading, which may compromise gasket sealing effectiveness over time. Further, the edges of the bending strip are unprotected. Therefore, the bending strip may become accidentally dislodged from the hole or otherwise damaged. In addition, the bending strips are often have limited effectiveness in gaskets that are subject to high frictional forces because the frictional forces cause buckling and sliding of the metallic plates, thereby resulting in the bending strips becoming partially disengaged from the first plate. Once again, sealing effectiveness is potentially compromised.